Measuring Long-Range Carrier Diffusion Across Multiple Grains in Polycrystalline Semiconductors by Photoluminescence Imaging

K. Alberi, B. Fluegel, H. Moutinho, R. G. Dhere, J. V. Li, A. Mascarenhas

Research output: Contribution to journalArticlepeer-review

35 Scopus Citations

Abstract

Thin-film polycrystalline semiconductors are currently at the forefront of inexpensive large-area solar cell and integrated circuit technologies because of their reduced processing and substrate selection constraints. Understanding the extent to which structural and electronic defects influence carrier transport in these materials is critical to controlling the optoelectronic properties, yet many measurement techniques are only capable of indirectly probing their effects. Here we apply a novel photoluminescence imaging technique to directly observe the low temperature diffusion of photocarriers through and across defect states in polycrystalline CdTe thin films. Our measurements show that an inhomogeneous distribution of localized defect states mediates long-range hole transport across multiple grain boundaries to locations exceeding 10 μm from the point of photogeneration. These results provide new insight into the key role deep trap states have in low temperature carrier transport in polycrystalline CdTe by revealing their propensity to act as networks for hopping conduction.

Original languageAmerican English
Article number2699
Number of pages7
JournalNature Communications
Volume4
DOIs
StatePublished - 2013

NREL Publication Number

  • NREL/JA-5900-60813

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